Pi-form metal phthalocyanine

ABSTRACT

THE NOVEL FORM OF PHTHALOCYANINE (PC), NAMELY N-FORM METAL-PHTHALOCYANINE, IS DISCLOSED METHODS FOR THE PREPARATION AND USE OF SAID FORM ARE ALSO DISCLOSED.

Jan. 2, 1973 Filed May- 21, 1971 INTENSITY (RELATIVE) INTENSITY (RELATIVE) I00 I I I I 1 P. J. BRACH ETAL 3,708,292

11" FORM METAL PHTHALOCYANINE 8 Sheets-Sheet 1 CUPc v 80-" so as 20 I5 IO 5 2 DEGREE 29 FIG. la

' I- l I I w.

CuPc v so so 25 20 l5 IO 5 2 Y DEGREE 29 FIG. lb

INVENTORS. Y PAUL J. BRACH HUGH A SIX ATTO-RNEY Jan. 2, 1913 P. J. ERACH Em 3,1082

11'- FORM METAL PHTHALOCYANINE Filed May 21, 1971 8 Sheets-Sheet 2 I I I I I CUPc I so X INTENSITY (RELATIVE) 3o 25 20 I5 Io s a DEGREE 29 FIG. lc

' I I I v I I CUPc I INTENSITY (RELATIVE) 3O 25 20 I5 l0 5 2 DEGREE 29 FIG. Id

P. J. BRAcH ETAL 3,708,292

'IF'FQRM METAL PHTHALOCYANINE 8 Sheets-Sheet 3 FIG. 3

8 C C mw film 1M [mm n H 1mm Jan. 2, 1973 Filed May 21, 1971 I700 I600 I500 l4 WAVENUMBER CM L l O O 0 0 0 O O 8 7 6 5 4 3 2 w 0 PERCENT TRANSM SS ON PERCENT TRANSM SS ON wwmwwwwm Jan. 2, 1973 Filed Bay 21, 1971 8 Sheets-Sheet 4 B- CuPc 0 1 l I l l l l l WAVENUMBER CM- FIG. 4

' X-CuPc o l l I 1 1 l l l l7O0 l5OO I3O0 2 uoo eoo 800 700 WAVENUMBER CM- I Jan. 2, 1973- BRACH ErAL 3,708,292

- IT-FORM METAL PHTHALOCYANINE I Filed May 21, 1971 a Sheets-Shed 5 I I r CoPc 7 6O INTENSITY (RELATIVE) so '25 20 l5 IO- 2 DEGREE 2e F/aaa I00 I I I l CoPc v so B A INTENSITY (RELATIVE) O 11 1. u 1 L- L 3o 20 I5 lQ I 5 2 DEGREE 29 Fl6.6b.

Jan. 2, 1973 P. J. BRACH E ,2

'IT-FORM METAL PHTHALOCYANINE Filed May 21, 1971 8 Sheets-Sheet 6 I I I I CoPc so X INTENSITY (RELATIVE) 3o 25 20 I5 IO 5 2 DEGREE 2e FIG-6c I I I l I CoPc so INTENSITY (RELATIVE) Q l I l I I 30 25 20 I5 IO 5 2 DEGREE. 29

FIG. 6a!

Jan. 2, 1973 BRACH ETAL IT-FORM METAL PHTHALOCYANINE 8 Sheets-5heet 7 Filed May 21, 1971 TT-CoPc o o O s a m w w 4 m.

PERCENT TRANSM SS ON www a CoPc l |eoo' 1400' I200 |00o 800 WAVENUMBER CM- FIG. 8

United States Patent 3,708,292 7T-FORM METAL PHTHALOCYANINE Paul J. Brach, Rochester, and Hugh A. Six, Webster, N .Y.", assignors to Xerox Corporation, Stamford, Conn. Filed May 21, 1971, Ser. No. 145,678 Int. Cl. G03g 5/04 U.S. Cl. 96-15 22 Claims ABSTRACT OF THE DISCLOSURE The novel form of phthalocyanine (Pc) namely vr-form metal-phthalocyanine, is disclosed. Methods for the preparation and use of said form are also disclosed.

BACKGROUND OF THE INVENTION This invention relates, in general, to phthalocyanine materials and, more specifically, to novel forms of metalphthalocyanines as well as to methods for the preparation and use of said forms.

Phthalocyanine, which also is known as tetrabenzotetraazaporphin and tetrabenzoporphyrazine, may be said to be the condensation product of four isoindole groups. Metal-free phthalocyanine has the following general structure:

In addition to the metal-free phthalocyanine of the above structure, various metal derivatives of phthalocyanine are known in which the two hydrogen atoms in the center of the molecule are replaced by metals from any group of the Periodic Table. Further, it is well known that from one to sixteen of the peripheral hydrogen atoms in the four benzene rings of the phthalocyanine molecule may be replaced by halogen atoms and by numerous organic and inorganic groups. The following discussion is directed primarily to nuclear-substituted metal-phthalocyanines.

Metal-phthalocyanines are known to exist in at least two well known polymorphic forms, namely, the alpha and beta. These forms may be easily distinguished by comparison of their X-ray diffraction patterns and/or infrared spectra. In addition to these two well known forms, which exist in both metalrontaining and metalfree phthalocyanine, the existence of additional polymorphs of metal-containing phthalocyanines have been disclosed, e.g., R-form disclosed in US. Pat. 3,051,721, delta form described in U.S. Pat. 3,160,635 and another delta form described in US. Pat. 3,150,150.

In re-issue application Ser. No. 741,815, now Reissue Pat. No. 27,117, it is disclosed that an especially sensitive form of metal-free phthalocyanine, known as X metal-free phthalocyanine, could be prepared by extended dry milling or grinding of the alpha or beta form metal-free phthalocyanine.

The known methods of preparing metal-phthalocyanines include the reaction of phthalonitrile with a metal or metal salt in quinoline or a mixture of quinoline and trichlorobenzene; the reaction of phthalic anhydride, phthalic acid, or phthalimide, urea metal salts, and a catalyst; the reaction of o-cyanobenzamide with a metal; and the reaction of phthalocyanine or replaceable metalphthalocyanine with a metal forming a more stable phthalocyanine. The metal-phthalocyanines prepared by the above methods are generally in the alpha or beta polymorphic forms.

While known metal-phthalocyanines are widely used in the preparation of inks and paints, there are several disadvantages associated with employing these materials in such a mode. For example, one drawback of employing many of the known metal-phthalocyanines in pigments is that they lack brilliance. Another serious disadvantage of using known metal-phthalocyanine polymorphs in pigments and paints is that they often recrystallize in the presence of heat and strong solvents. Electrophotographic plates comprising metal-phthalocyanines in a binder are disclosed in copending application Ser. No. 518,450, filed Jan. 3, 1966.

Thus, there is a continuing need for a metal-phthalocyanines with a brighter appearance, greater stability to recrystallization in the presence of heat and strong solvents, and increased electrical photosensitivities.

SUMMARY OF THE INVENTION It is, therefore, an object of this invention to provide metal-phthalocyanines devoid of the above noted disadvantages.

It is another object of this invention to provide novel metal-phthalocyanines of higher brilliance than known metal-phthalocyanines.

It is still another object of this invention to provide metal-phthalocyanines which are unusually stable to recrystallization in the presence of heat and strong solvents.

It is yet another further object of this invention to provide metal-phthalocyanines with satisfactory dispersibility properties.

It is still another object of this invention to provide metal-phthalocyanines having suitable properties for use in electrophotographic imaging systems.

It is still another object of this invention to provide metal-phthalocyanines with highly desirable colors.

The foregoing objectives, and others, are accomplished in accordance with this invention, generally speaking, by providing a novel polymorphic form of metal-phthalocyanine, namely, the 1rmetal-form. As described above, the rrmetal-form has utility as a paint component, ink component, and as a photoconductive material in electrophotography when dispersed in a binder and coated on a substrate. Inks and paints prepared with the vr-metal polymorph demonstrate surprising brilliance whi-le electrophotographic plates comprising the vr-metal form exhibits photosensitivities suitable for use in electrophotographic processes. 1r-metal phthalocyanines are equivalent in photosensitivity to B-metal phthalocyanines, the X-form exhibiting greater photosensitivity then either of the aforementioned.

Thermal stability of ar-metal phthalocyanine are found to be good, e.g., 1r-CUPC melts at approximately 610 C. without undergoing decomposition or transformation to another polymorphic form while the a and X-polymorphs are found to convert to 3 at temperatures above 270 C. B-CuPc is found to melt at 610 C. without undergoing any change analogous to the stable 1r-CuPc. While ot-metal Po and X-metal Pc are found to convert to the [El-polymorph at room temperature when treated with aromatic solvents such as benzene or xylene over a period of a few hours and even more rapidly in hot solvents, 1r-CLIPC and 1r-COPC exhibit stabilities similar to the more stable [3-Cu and CoPc fi-metal Po does not alter its morphic form in refluxing aromatic solvents. 1r-Cl1PC is completely stable in refluxing benzene at a temperature of 78 C. even after 96 hours of treatment. rr-COPC in boiling xylene at 140 C. for 30 hours does not result in conversion. Thus it is seen that the desirable color of 1r-CUPC is preserved under solvents which are seen to alter the color of a-CUPC to that of fi-CuPc. After 72 hours at 140 C. in the same solvent, considerable conversion to the ,8 polymorph takes place so that vr-metal phthalocyanines are seen to be less stable than B-MPcs but much more stable than either aor X-metal phthalocyanine in the presence of hot aromatic solvents.

The novel system for the preparation of wr-metal-form phthalocyanine comprises mixing, at a suitable reaction temperature, phthalonitrile, a metal salt and ammonia in an alkylalkanolamine solvent or 1,3-diimino-isoindoline and a metal salt in a non-ammonia saturated alkyla-lkanolamine solvent, and heating the mixture to about reflux temperature.

Any suitable solvent may be used in this system. Typical solvents are alkylalkanolamines, such as,

Z-dimethylaminoethanol, 1-dimethylamino-2-propanol, 1-diethylamino-2-propanol, 2dimethylamino-2-methyl l-propano-l, 2-diethylaminoethanol,

3-dimethylaminol-propanol,

2- di-iso-propylamino ethanol, Z-butylamino-ethanol, Z-dibutylamino-ethanol,

2- dibutylamino-ethanol,

2 2- (diethylamino ethyl) amino] ethanol, 2,2'- butylimino diethanol, 2-ethylaminoethanol,

2,2- (ethylimino) diethanol, 2-methyl-aminoethanol,

2,2'-(methylimino diethanol,

2- (iso-propylamino ethanol,

2,2'- iso-propylimino diethanol,

2,2'- tertiary-butylimino diethanol, and 3-diethylaminol-propanol, among others.

Although any suitable solvent may be used in this system, it is preferred that solvents containing a primary alcohol group be employed in order to obtain a higher yield of the final desired product. While any suitable solvent containing a primary alcohol group may be used in this invention, significantly high yields of 1r-metal-form phthalocyanine are obtained with the use of Z-dimethylamino-ethanol and, accordingly, this particular solvent is most preferred- Although the synthesis of the present invention may be carried out at any suitable temperature, the range of about 120 C. to about 280 C. has been found convenient. While any appropriate temperature may be employed, it is preferred that a temperature generally in the range of about 135 C. to about 150 C. be used in order to obtain higher yields of the desired final product.

The total reaction time of the instant invention is about 10 to about 70 minutes depending on the particular solvent and the temperature employed. It the reaction proceeds much past about 90 minutes reaction time, beta metal-phthalocyanine formation begins to take place and mixtures of 1r-form and beta-form phthalocyanines are obtained. A preferred reaction time is about 30 to about 55 minutes with Z-dimethylaminoetheinol in order to obtain a high yield of pure 1r-form metal phthalocyanine.

Any suitable mixing process may be used to slurry the phthalonitrile in the solvent mix. A complete conversion from phthalonitrile is attained where the mixture is stirred during the conversion and ammonia gas is bubbled through said mixture. The addition of ammonia gas is not necessary where 1,3-diimino-isoindoline is used. The mixing may be carried out by milling with glass or steel balls or merely by stirring with a magnetic bar or simple rotating agitator. While the phthalonitrile or 1,3-diiminoisoindoline may be dissolved in the solvent at any suitable temperature, it is preferable to dissolve these materials when said solvent is heated to about 120 C.

After the phthalonitrile or 1,3-diimino-isoindoline is added to the hot solvent, ammonia is added in the case of phthalonitrile and then a metal salt is added to the mixture and the temperature immediately rises to reflux due to a rapid exothermic reaction. The mixture is then maintained at reflux temperature for about 5 to about minutes depending upon the solvent used, filtered hot, washed, and dried.

The rr-form metal phthalocyanine of the present invention may be' used to prepare electrophotographic plates and be used in electrophotographic processes as described in co-pending application Ser. No. 518,450 with excellent results.

In addition to toner development there are many other ways of utilizing the electrostatic latent image formed on the imaging members hereof some of which are described hereinafter.

For example, the migration imaging process of co-pending application Ser. No. 483,675, filed Aug. 30, 1965, now US. Pat. No. 3,656,990 may be used to cause an imagewise migration of a fracturable or microscopically discontinuous thin photoconductive layer into an underlying plastic layer in image configuration, generally corresponding to the electrostatic latent image pattern.

Another mode of utilizing the electrostatic latent images formed on the imaging members hereof is to transfer the charge pattern to another layer by bringing the two layers into very close proximity and utilizing breakdown techniques as described, for example, in Carlson Pat. 2,982,647 and Walkup Pats. 2,828,814 and 2,937,943. For example, the layer to which the charge image is transferred may be a surface deformable material which may be caused to deform in image configuration as disclosed in Gunther et a1. Pat. 3,196,011.

The electrostatic latent image may also be directly read out utilizing devices such as electrometers which detect potential differences which may be translated into giving the graphic information that was represented by the original electrostatic latent image.

Insulating receiving sheets may be brought into contact with the electrostatic latent image bearing plates hereof and the receiving sheet developed with toner utilizing techniques which permit a plurality of such copies to be made from one master electrostatic latent image.

As disclosed in copending application Ser. No. 867,049, filed Oct. 16, 1969, now US. Pat. No. 3,551,146 wherein a relatively more conductive image receiving sheet including paper may be placed in contact with the electrostatic latent image bearing plates hereof inducing an image in said receiving sheet which induced image can be developed by techniques which permit or more such developed receiving sheets to be made from a single master electrostatic latent image.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The following examples will further define various preferred embodiments of the present invention. Parts and percentages are by Weight unless otherwise specified.

The crystal forms of metal-phthalocyanine produced in each of the following examples are analyzed by conventional X-ray and infrared analyses methods. The X- ray and infrared curves produced by the materials prepared in each of the following examples are compared to curves for known alpha, beta, and X-form metalphthalocyanines employing X-ray radiation CuK;

radiation of A=1.5418 A.U.

Example I About 200 ml. of Z-dimethylaminoethanol is placed in a 4-neck, 500 ml. round bottom flask equipped with a mechanical stirrer, reflux condenser, thermometer, and gas inlet tube. About 65 g. of phthalonitrile is added and the mixture is heated with stirring to about 90 C. A steady stream of ammonia gas is then passed through the resulting solution while heating is continued to raise the temperature to about 120 C., at which point about 11 g. of anhydrous cuprous cyanide is added and the reaction temperature immediately rises to reflux or about 135 C. Ammonia introduction and stirring is continued for about 50 minutes while the temperature is maintained at about 135 C. The mixture is then filtered hot and the residue is thoroughly washed with ethanol, acetone, and methanol. An aqueous solution of sodium cyanide is used to remove unreacted cuprous cyanide. After this treatment, the blue solid is washed to a pH of 7 with water, followed by 1 N hydrochloric acid, then water, then a 1% solution of ammonium hydroxide, then water, and finally with methanol. The product is then oven-dried at about 70 C. for about 2 hours. The resulting material yield about 80%, is brilliant royal blue in color. This material is subjected to conventional X-ray and infrared analyses. X-ray and IR data which are shown in FIGS. 1d and 2 respectively, are compared to known IR and X-ray data for the alpha copper, beta copper, and X-form copper polymorphs, respectively (see FIGS. 1a, 1b, 1c and FIGS. 3, 4, and 5 respectively). Comparison of the X-ray and IR data for the vr-copper polymorph with the other copper phthalocyanine polymorphs shows the following:

In FIG. 1, Bragg angles (20) are observed at 6.9, 6.8, 7.3 for e-form copper phthalocyanine, 7.0 and 9.2 for fiform copper phthalocyanine and 7.7 and 9.5 for X-form copper phthalocyanine which are clearly different from the 1r-form copper phthalacyanine which exhibiting lines at 5.1, 8.8 and 10.0. Literature data confirms the band at 6.9 for a-form copper phthalocyanine.

The most salient features of the infrared spectra for the copper phthalocyanine polymorphs are shown in the following table:

Position of absorption bands are shown in wavenumber cm. and relative intensities are labeled as v.s.=very strong; s. =strong; m.=medium and w.=weak.

Comparison of FIGS. 2-5 and Table I clearly shows shifting of the 0-H out of plane bending mode from 722.5 in a-form copper phthalocyanine to 727.5 in X- form phthalocyanine, to 728 in vr-form copper phthalocyanine and 730.5 in B-form phthalocyanine. Shifting of this absorption band which is the most intense band in the spectra suggests very significant changes in intermolecular overlapping of pi orbitals and hence is evidence of different crystal structures. The small difference noted between X and vr-fOlIIlS, 727.5 to 728 cm. respectively, suggests very similar overlapping in these two crystalline forms, however, examination of the bands near 780 cm.- 774 in X and 781 in 1r-form clearly differentiate between them. The gross differences in the X-ray diffraction patterns between X and 1r (FIG. 1) offer a more pronounced distinction between these two forms.

Therefore, each of the four polymorphic forms of copper phthalocyanine can be identified by either their X- ray diffraction patterns or by their infrared spectra and unequivocal confirmation can be obtained by simultaneously applying both techniques.

Example II About 175 ml. of 2-dimethylamineothanol is placed in a 500 ml. flask, equipped as in Example I. About 65 g. of phthalonitrile is added and the mixture is heated with stirring to about C. A steady stream of anhydrous ammonia gas is passed through the resulting solution and said solution is heated slowly to about C., at which point approximately 16.2 g. of anhydrous cobaltous chloride is added and the reaction temperature immediately rises to reflux or about C. Ammonia introduction and stirring is continued for about 10 minutes while the temperature is maintained at about 135 C. A purple precipitate is removed from the hot reaction mixture by filtration and thoroughly washed with ethanol and acetone. The resulting purple needle-like crystals are oven dried at about 75 C. for about 1 /2 hours. The brilliant purple material yield of about 85%, is then subjected to conventional X-ray and infrared analyses. X-ray and IR data which are shown in FIGS. 6d and 7 respectively, are compared to known X-ray and IR data for the alpha cobalt, beta cobalt, and X-form cobalt polymorphs, respectively. (See FIGS. 6a, 6b, 6c, 8, 9, and 10 respectively.)

X-ray diffraction patterns for cobalt phthalocyanine polymorphs are very similar to those shown above for the copper phthalocyanine forms. Namely, lines are observed at 6.8 and 7.4 for a-form cobalt phthalocyanine, 7.2 and 9.4 for fi-form cobalt phthalocyanine, 7.8 and 9.5 for X-form cobalt phthalocyanine and 5.0, 8.7 and 10.0 for 1r-form cobalt phthalocyanine. All lines are reported as Bragg angles (20).

Characteristic infrared absorption bands for the polymorphic forms of cobalt phthalocyanine include those shown in Table II:

Position of absorption bands are shown in wavenumber cm? and relative intensities are labeled as v.s.=very strong; s.=strong; m.=medium and w.=weak.

As in the case of copper phthalocyanine, the C-H out of plane bending is a sensitive indicator of crystalline form in the cobalt phthalocyanines. This absorption band appears at 723.5 cm." for the a-form, 733 for B and 731.5 for both X and 11' forms. Also similar to the CuPc is the position of the bands near 780 cm. in CoPc which is observed at 771 for the a-form, 782 in the 5 and 11' forms and 778 in the X form. Other characteristics of the spectra such as the differences in the 1000-1200 cm.- region also permit differentiation of the four polymorphic forms of cobalt phthalocyanine. Therefore, as with CuPc's, comparison of X-ray diffraction patterns rather than IR data provides a more substantial standard with which to distinguish the 1r-form from others While the use of both unequivocally defines the crystalline modification.

Example IH The experiment of Example I is repeated, except that about 250 ml. of 3-dimethylamino-l-propanol is employed in place of the Z-dimethylaminoethanol, about 100 g. rather than 80 g. of phthalonitrile are used, and heating is maintained for about 30 minutes rather than about 50 minutes prior to filtering. The product obtained in a yield of about 30% when subjected to analyses is proven to be 1r-Cl1PC.

Example IV As a control for the conversion process of Example III the experiment is repeated, allowing the mixture to be heated for 90 minutes rather than 30 minutes prior to filtering. X-ray and infrared analyses show the product to be a mixture of ar-form and beta copper phthalocyanines.

Example V The conversion process of Example I is attempted, allowing the mixture to be heated for hours rather than 50 minutes prior to filtering. X-ray and infrared analyses show complete conversion to beta copper phthalocyanine.

Example VI The experiment of Example I is repeated using l-dimethylamino 2 propanol having a boiling point about 126 C. in place of Z-dimethylaminoethanol having a boiling point about 135 C. The percentage yield of the final product, which is found by X-ray and infrared analyses to be rr-fOIIIl copper phthalocyanine, is significantly less than the percentage yield in Example I or about 0.1% yield as opposed to about 80%.

Example VII About 250 ml. of Z-dimethylaminoethanol is placed in a 500 m1. flask and heated to about 120 C. at which temperature about 60 g. of 1,3-diiminoisoindoline is added. At this point, about 16.5 g. of anhydrous cobaltous chloride is added and the reaction temperature immediately rises to reflux or about 135 C. Stirring and heating is maintained at about 135 C. for about 20 minutes. The mixture is then filtered hot, washed with ethanol, acetone, and methanol, and air-dried. The resulting product is subjected to conventional X-ray and infrared analyses. The product obtained in a yield of about 25% when subjected to analyses is proven to be 1r-fOI'm cobalt phthalocyanine.

Example VIII A coating solution is prepared by dissolving about 70 parts Epon 1007, an epoxy resin available from the Shell Chemical Company, in about 80 parts ethyl Cellosolve, an ethylene glycol monoethylether available from the Union Carbide Corporation. To this solution is added about 40 parts Methylon 7520, a phenolic resin available from the General Electric Company, and about 9 parts Uformite F-240, a urea-formaldehyde resin available from the Rohm & Haas Company. The mixture is stirred to insure complete solution. To this solution is added about 20 parts of the vr-form copper phthalocyanine prepared as in Example I. An aluminum substrate is coated with this mixture to a dry film thickness of about 40 microns. The plate is heated to about 180 C. for about 2 hours to cure the resins. The plate is electrostatically charged by means of a corona discharge device operating at a positive potential of about 6,000 volts. The plate is exposed for about 1 second by projection using a blackand-white transparency in a Simmons-Omega D3 Enlarger equipped with an 7/ 4.5 lens and a tungsten light source operating at 2950 K. color temperature. The illumination level at the plate is about 4 foot-candles. The resulting latent electrostatic image is developed by cascading electroscopic marking particles across the surface thereof as described by Walkup in U.S. Pat. 2,618,551. The resulting powder image is electro'statically transferred to a paper receiving sheet as described by Schalfert in U.S. Pat. 2,576,047. The image on the sheet is of good quality and corresponds to the projected image. The plate is then reused by the above-described process until 100 copies are produced. The image on the 100th copy is as of good quality as that produced on the first sheet and corresponds to the projected image.

8 Example IX Example VIII is repeated using the vr-form cobalt phthalocyanine of Example H. Images of good quality corresponding to the originals result in each case. After producing about 150 copies, the images produced in each case appear to be as good a quality as the first reproduced image.

While specific components of the present system are defined in the working examples above, any of the other typical materials indicated above may be substituted in said working examples if appropriate. In additon, many other variables may be introduced in the present process, such as further purification steps or other reaction components which may in any way affect, enhance, or otherwise improve the present process.

While various specifics are cited in the present application, many modifications and ramifications vw'll occur to those skilled in the art upon a reading of the present disclosure. These are intended to be encompassed within the scope of this invention.

What is claimed is:

1. Nuclear substituted metal phthalocyanine in the 1rform having an X-ray dilfraction pattern exhibiting strong lines at Bragg angles of 20 equal to about 5.1, 8.8 and 10.0 using CuK;

radiation of A=1.5418 AU.

2. The composition of claim 1 wherein said metal is selected from the group consisting of copper and cobalt.

3. The composition of claim 1 wherein said nuclearsubstituted metal phthalocyanine is peripherally unsubstituted.

4. A method of preparing wr-form metal phthalocyanine comprising the steps of (a) mixing phthalonitrile in pre-heated alkylalkanolamine solvents adding an anhydrous metal salt, whereby the temperature of the mixture rises to above reflux temperature; and

(b) maintaining said temperature for about 10 to about 70 minutes.

5. The method of claim 4 wherein said alkylalkanolamine contains a primary alcohol group.

6. The method of claim 4 wherein said alkylalkanolamine is Z-dimethylaminoethanol.

7. The method of claim 4 wherein said phthalonitrile is mixed with the solvent when said solvent is at a temperature of about C.

8. The method of claim 4 wherein said reflux temperature is maintained for about 30 to about 55 minutes.

9. A method of preparing 1r-form metal phthalocyanine comprising the steps of:

(a) mixing 1,3-diimino-isoindoline in a pre-heated alkylalkanolamine solvent;

(b)adding an anhydrous metal salt, whereby the temperature of the mixture rises to about reflux tempera ture, and

(c) maintaining said temperature of about 10 to about 70 minutes.

10. The method of claim 9 wherein said alkylalkanolamine contains a primary alcohol group.

11. The method of claim 9 wherein said alkylalkanolamine is 2-dimethylaminoethanol.

12. The method of claim 9 wherein said 1,3-diiminoisoindoline is mixed with the solvent when said solvent is at a temperature of about 120 C.

13. The method of claim 9 wherein said reflux temperature is maintained for about 30 to about 55 minutes.

14. An electrophotographic plate comprising:

(a) a conductive substrate; and

(b) a layer overlying said substrate, said layer comprising 1r-form metal phthalocyanine having an X-ray ditfraction pattern exhibiting strong lines at Bragg angles of 20 equal to about 5.1, 8.8 aid 10.0 using CuK;

radiation of A=1.54l8 A.U. dispersed in an insulating resin binder.

15. The plate of claim 14 wherein said metal phthalocyanine is selected from the group consisting of Ir-form copper phthalocyanine, 1r-form cobalt phthalocyanine, and mixtures thereof.

16. The plate of claim 14 wherein the ratio of said phthalocyanine to said resin binder ranges from about 2: l, by weight, to about 1:15 by weight.

17. An electrophotographic imaging process comprising the steps of:

(a) providing an electrophotographic plate comprising a conductive substrate overcoated with a layer comprising 1r-form metal phthalocyanine having an X-ray difiraction pattern exhibiting strong lines at Braggangles of 20 equal to about 5.1, 8.8 and 10.0 using CuKE 18. The process of claim 17 wherein said metal phthalo- 3 cyanine is selected from the group consisting of 1r-form copper phthalocyanine, 1r-forrn cobalt phthalocyanine, and mixtures thereof.

10 19. The process of claim 17 wherein the ratio of said phthalocyanine to said resin binder ranges from about 2:1, by weight, to about 1:15, by Weight.

20. The process of claim 17 wherein said electrostatic 5 image is formed by uniformly electrostatically charging the surface of said plate and exposing said plate of an image of activating electromagnetic radiation.

21. The process of claim 17 wherein said visible image is transferred to a receiving sheet and steps (b) and (c) are repeated.

22. An electrophotographic imaging process comprising the steps of:

(a) providing an electrophotographic plate comprising a conductive substrate overcoated with a layer comprising ar-form metal phthalocyanine having an X-ray diffraction pattern exhibiting strong lines at Bragg angles of equal to about 5.1, 8.8 and 10.0 using CuKZ 20 radiation of \=l.5418 A.U. dispersed in an insulat ing resin binder; and (b) forming an electrostatic latent image on said plate.

References Cited UNITED STATES PATENTS 3,509,146 4/1970 Weinberger et a1. 260250 Re. 27,117 4/ 1971 Byrne et a1 260-314.5

0 JOHN C. COOPER III, Primary Examiner US. Cl. X.R. 

